The vomit came without warning.
Ethan made it to the kitchen sink, barely. Coffee and bile and something that tasted like copper. When he could breathe again, he ran the water and watched it spiral down the drain, hands braced against the counter. The left one shook so badly it seemed to blur.
The protein shake sat in the refrigerator door, vanilla-flavored, seventeen grams per serving. He'd promised Dr. Reeves. He twisted the cap off, managed three swallows before his stomach threatened mutiny. Close enough.
The Engine was brighter when he returned.
Not physically—the obsidian disc looked the same, its sigils flowing in their eternal patterns. But something had changed in the quality of its presence. Like a conversation happening just below the threshold of hearing.
He pressed his palm to the surface and fell through.
---
Forty-seven thousand years had passed since the bacterial negotiations.
The stromatolites had developed something new: specialized chambers that resonated at specific frequencies. Ethan drifted through the reef lattices, watching vibrations propagate through calcium carbonate walls. The patterns were too regular to be accident. Chambers tuned to harmonic intervals. Nodes that amplified or dampened incoming waves.
Communication.
Not language—nothing semantic. But information transfer. A colony on the eastern shelf had discovered a new metabolic pathway, and within three thousand years, communities five hundred kilometers away were implementing variations. The vibrational patterns carried templates. Blueprints encoded in frequency.
He mapped the networks. Resonance pathways connecting reef systems across entire ocean basins. Some colonies served as relay stations, their architecture optimized for signal propagation. Others were repositories, their chamber-patterns storing information in crystallized form.
The stromatolites had invented writing before they invented neurons.
Ethan pulled back to watch a resonance cascade ripple across the continental shelf. Colonies vibrating in sequence, passing information hand-to-hand across the abyss. The pattern was elegant. Wasteful in some ways—thousands of years for a message to cross the planet—but robust. No single point of failure. No central coordination.
Distributed intelligence in the key of calcium carbonate.
He was about to trace the oldest signal pathways when the interference started.
---
It began as a dissonance in the harmonic networks.
At first, Ethan thought it was background noise—tidal forces, tectonic shifts, the ambient chaos of a living planet. But the pattern was too persistent. Too structured. Something was broadcasting a counter-frequency into the stromatolite networks.
He focused on the source.
Deep water. Below the photic zone, where the last stromatolites had only recently established colonies in chemosynthetic partnerships. The signal originated from a trench system, regular pulses that disrupted the reef communications without destroying them.
Jamming. Or...
Ethan descended.
The source wasn't stromatolite. The architecture was wrong—no calcium carbonate, no photosynthetic partners. These structures were silicon-based, crystalline formations that had grown around hydrothermal vents. They'd developed independently, following a completely different evolutionary strategy.
And they were answering the stromatolite broadcasts.
Not copying them. Responding. The silicon colonies emitted frequencies that interlocked with the stromatolite patterns like puzzle pieces, creating hybrid harmonic structures. Two completely separate evolutionary lineages, communicating through stone.
The first conversation between alien minds.
Ethan watched for what must have been hours—twelve thousand Aethon years. The silicon colonies introduced variations, new harmonics the stromatolites had never produced. The stromatolites adapted, incorporating the foreign frequencies into their networks. Information flowing both ways. Mutual transformation.
Symbiosis at the level of ideas.
He was documenting the exchange patterns when his chest seized.
---
The apartment materialized around him in fragments.
Floor. Ceiling. The Engine's obsidian surface against his cheek. His lungs refused to work, muscles locked in spasm. Somewhere in his failing body, neurons were misfiring, motor control dissolving like sand castles at high tide.
Not yet. Not this fast.
He couldn't reach his phone. Couldn't call Maya, couldn't call anyone. Could only lie there on the floor while his diaphragm slowly, reluctantly, remembered how to function.
Air came back in shallow gasps.
The tremor in his left arm had spread to both legs now. He could feel it—the progressive deterioration, each nerve pathway surrendering in turn. Dr. Reeves had said eighteen months. Maybe he'd been optimistic.
Ethan managed to sit up. The room spun, settled.
The protein shake sat on the coffee table, mostly full. The laptop screen had gone dark. The Engine pulsed with its steady rhythm, patient as continental drift, indifferent as evolution itself.
Inside it, two forms of stone-based life were teaching each other to sing.
Outside it, a man was learning what it meant to be substrate.
He reached for the Engine again. His hand shook so badly he had to use both arms to steady it. The obsidian felt warm against his palm, almost alive.
Almost sympathetic.
The sigils shifted, and in their pattern, Ethan saw something he'd missed before: a frequency, very faint, that matched no structure in Aethon. It pulsed in time with his heartbeat.
The Engine was listening to him too.